Fix VPS Vault OIDC login: missing redirect_uri + missing DNS

Two pre-existing gaps (not caused by this session's earlier work),
surfaced when the user started testing the VPS's standby Vault
(infrastructure/vps-standby/vault/) login via Authentik SSO:

1. VPS Vault's own auth/oidc/role/default allowed_redirect_uris only had
   vault.kube.huskypup.net (home) and localhost:8250 - never had
   vault.vps.huskypup.net registered, even though VPS's Vault shares the
   same Authentik OAuth2 provider/client_id as home's. Fixed on both
   sides: the shared blueprint (redirect_uris list) and VPS Vault's own
   role config directly (separate Vault instance/backend, needed its own
   write).

2. auth.kube.huskypup.net (Authentik itself) had NO public DNS record at
   all - it only ever resolved via UniFi's local DNS for home-LAN
   clients. Vault's OIDC backend runs server-side on the VPS and needs to
   fetch Authentik's discovery document directly - it silently returned
   an empty auth_url because it couldn't resolve the hostname at all
   ('missing auth_url' in Vault's UI, root cause only found by checking
   DNS resolution from inside the VPS's own vault pod). Added a public
   Cloudflare A record, same pattern as vault.kube.huskypup.net and
   pg-authentik.ha.huskypup.net earlier - user confirmed before adding,
   given it's Authentik itself. This likely also fixes OIDC for any other
   VPS-hosted app doing SSO against home's Authentik, not just Vault.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

infrastructure/authentik/vault-blueprint.yaml

@@ -45,6 +45,15 @@ spec:
                 redirect_uris:
                   - url: "https://vault.kube.huskypup.net/ui/vault/auth/oidc/oidc/callback"
                     matching_mode: strict
+                  # VPS's own standby Vault instance (infrastructure/vps-standby/vault/)
+                  # shares this SAME Authentik provider/client_id - found missing
+                  # 2026-08-21 while testing VPS vault login ("missing auth_url" -
+                  # Vault silently returns no auth_url when the UI's computed
+                  # redirect_uri isn't in allowed_redirect_uris; same fix needed on
+                  # the VPS Vault's own auth/oidc/role/default, done separately since
+                  # it's a fully independent Vault instance/backend).
+                  - url: "https://vault.vps.huskypup.net/ui/vault/auth/oidc/oidc/callback"
+                    matching_mode: strict
                   - url: "http://localhost:8250/oidc/callback"
                     matching_mode: strict
                 property_mappings: